This invention involves devices for moving at least two masses with respect to a central axis of symmetry in a given direction. In particular, the devices permit the movement on a ring of two cameras for tomographic scanning of the body of a patient, for example.
There already exists a technique called tomography that basically permits the formation of an image, layer by layer, of a given body by means of cameras adapted, for example, from those used for X-rays or the like. Very simplistically, a tomographic scanner (CAT scanner) comprises a frame, sometimes mounted on rails, with a central opening into which a bed on which a patient is lying can be moved. On this frame is usually mounted a rotating plate supporting two components permitting the formation of images, as described above. These two components are usually two cameras arranged symmetrically with respect to the center of the plate and thus to the central opening through which the patients body moves.
For the generation of high-quality images of the internal organs of the patient, it is necessary, for the essential purpose of accommodating and focusing the optical components, to move the two cameras symmetrically with respect to the axis of the turning plate. However, the cameras used in the technique of tomography, on the one hand, are relatively heavy and, on the other hand, hang over the plate, since the patients are in a horizontal position. It is thus conceivable that the movement and maintenance of these overhanging cameras pose technical problems that are relatively difficult to solve, in light of the fact that to obtain clear images, it is necessary that these cameras be positioned perfectly with respect to the center of symmetry and that they move as precisely as possible, specifically, without any play and without being subject to parasite vibrations.